Concentric-hopper batch-feeder



June 23, 1959 R, BLACKMAN ETAL 2,891,782

CONCENTRIC-HOPPER BATCH-FEEDER I Filed Feb. 10, 1956 lNVENTOR PAUL P.- BLACK M AN PQESSU 2E GAS SOURCE.

WALT Q MOEM BY K W ATTORNEYS r: 2,891,782 1C6 Patented June 23, 1959 CONCENTRIC-HOPPER BATCH-FEEDER Paul R. Blackman, Cranford, and Walter B. Moen, Berkeley Heights, N.J., assignors to Air Reduction Company, Incorporated, New York, N.Y., a corporation of New York Application February 10, 1956, Serial No. 564,668

4 Claims. (Cl. 266-34) This invention relates to apparatus for the immediate successive feeding of dissimilar finely-divided materials into a carrier gas stream for introduction beneath the surface of a liquid and more particularly is concerned with the introduction of calcium carbide and then a nodulizing agent into molten cast iron.

In order to improve the properties of cast iron, the introduction of various finely-divided treating agents into molten cast iron beneath the surface thereof has been practiced. The finely-divided treating agents are carried by a gas under pressure so that the hydrostatic head of molten iron is overcome and additionally in some cases so that the agents are projected into the molten iron. This method of introduction permits the small particles of the treating agents to affect rapidly and beneficially the iron due to the extended surface contact. This treatment often requires the introduction of two treating agents in succession. For example, molten cast iron can be first treated with finely-divided calcium carbide for desulfurization and secondly with a finely-divided nodulizing agent such as a magnesium-containing material. In such a treatment, it is highly desirable that the agent be introduced in immediately after the first agent and that the entire treatment he performed by a single simple piece of equipment which is free of moving parts insofar as the successive feeding is concerned.

The primary object of the present invention is to provide an improved apparatus for the successive feeding of finely-divided materials into a feed arrangement where the materials are admixed with a carrier gas and thereafter introduced into a liquid.

The preferred embodiment of the invention includes a hopper within a hopper for the two different finely-divided materials and means for introducing a gas under pressure into both hoppers. The arrangement between the bottom discharge means of the hoppers is such that the inner hopper feeds downwardly first to a gas-pick-up device and then the outer hopper feeds. This successive feeding is accomplished without mixing and without movement of mechanical parts such as valves or trap doors. The feature of non-mixing, successive feeding of two finely-divided materials is achieved by the combination of the slanted wall of the outer hopper, the cylindrical neck of the inner hopper and the spacing among the bottom of the neck, the adjacent slanted wall and the bottom outlet of the outer hopper.

The foregoing and other features of the invention are described in greater detail hereinafter with reference to the accompanying drawing, in which is shown a partial cross-section view of the preferred embodiment of the invention.

The apparatus shown in the drawing comprises a pressure-regulated gas supply source 11. This source in cludes a conventional gas cylinder, shut-off valve, pressure regulator, and flow-meter (not shown). Source 11 is connected by a flexible conduit to valve-controlled conduits leading to the outer hopper 13 and to the carrier gas inlet 15 below the hopper. The outer hopper 13 has a cylindrical body 17, a truncated conical bottom section 19 having a bottom opening and an apertured top wall 21. Opening 22 in the top wall is made gastight by removable cover 23. Cover 23 is held in pressure-tight engagement with top wall 21 by means of clamp 25. A pressure gauge 27 advantageously is mounted on top wall 21 to show the pressure within the hopper. A safety valve 28 is also mounted in the top wall to protect the feed hopper from too high an internal pressure.

Within outer hopper 13, the inner hopper 31 is positioned by means of three equilaterally-spaced trapezoidal spacers 32. One spacer 32 appears in the drawing. Inner hopper 31 like outer hopper 13 has a cylindrical section 33, an inverted truncated conical bottom 35 and a cylindrical neck 36 connected to the bottom edge of bottom 35. it is to be noted that spacers 32 are attached to neck 36 and rest on inclined wall 19 of the outer hopper 13. The small annular opening 37 between the inclined wall 19 and the bottom of neck 36 permits material to be fed from the outer annular hopper. Truncated conical top wall 38 of inner hopper 31 has a removable plug 39 so that the plug can be removed for charging material into the inner hopper. This conically-topped plug also facilitates charging the outer hopper. Admitting gas under pressure into the inner hopper I is accomplished merely by removing the plug or grooves can be provided in the depending neck of plug 39. Top wall 38 has an included angle of 90 degrees. Bottom wall 35 and bottom wall 19 both have the same included angle which is 60 degrees.

Means including gas inlet pipe 41 are provided for admitting gas under pressure into the interior of hopper 13 and hopper 31. A valve 43 in pipe 41 controls the admission of gas. Conventional means (above-mentioned but not shown) such as a pressure regulator, a fiow meter and a shut-off valve are also provided as part of the gas source. It is apparent that these items are upstream of the juncture of pipe 41 and pipe 45 having needle valve 46 which extends to the carrier gas inlet 15.

A discharge pipe 51 extends from the bottom circular outlet 53, formed by the bottom of conical section of the outer hopper, and connects through pipe 54 to a treating agent control valve 55 of the open-closed type. This valve provides an unobstructed passage from pipe 51 to pipe 57 which is connected to the bottom outlet of valve 55.

An orifice plate assembly 61 is connected to the bottom of intermediate pipe 57 and includes a circular orifice plate 63 having a centrally-located orifice hole 65. The orifice plate is mounted by clamping it between the engaging components of a conventional pipe union. The

orifice plate can be changed to provide a difierent size orifice hole and hence effect a change in the range 0 flow of treating agents.

A flow of carrier gas is provided downstream of orifice q plate 63 in pipe 67 by means of nozzle 69 which is connected to the gas supply 11 by means of pipe 45 having needle valve 46. This valve 46 regulates the amount of and the pressure of gas which enters nozzle 69 and the pressure of the gas in the hoppers. Nozzle 69 is arranged to direct the flow of gas in the direction which the treating agent is to take, namely downwardly.

Pipe 67 is connected to an injection tube assembly 71 which is adapted to he placed on the top edge of a ladle or a runner in an iron foundry or the like. The injection tube assembly is comprised of an upper steel pipe 73 suitably connected to pipe 67, a shield 75 which is attached to pipe 73 and has brackets 77, and injection tube 79 connected to pipe 73 beneath the shield '75. Brackets 77 provide one form of means for carrying the hopper and connected apparatus and positioning the injection tube in a ladle. Injection tube 79 is made of a refractory ma terial, such as electrode-type graphite or high alumina material. It is to be understood that the finely-divided materials herein referred to are of a very small particle size. Calcium carbide typical will pass through a 16 mesh Tyler screen and be substantially completely retained on 200 mesh screen. About 80% of the material will be retained on 100 mesh screen. The nodulizing agent for the outer hopper is about the same size. The density of the injection stream should be from about /42 cubic feet of gas per pound of treating agent.

The feature of providing immediate successive feeding of the material in inner hopper 31 and then the material in the outer annular hopper 13 without gates or other moving parts is accomplished by means of the arrangement and sizes of neck as, spacers 32, the opening in the bottom of the outer hopper 53 and the inclined wall 19. The inside diameter of opening 53 is 1" while the inside diameter of neck 36 is l fii". The vertical length of neck 36 is l" and the distance from the bottom of the neck to the horizontal plane of opening 53 is Spacers 32 are of such size that the perpendicular distance from the inner surface of inclined wall 19 to the outer lower edge of neck 36 is /s". Thus, the annular opening 37 has an effective width of A; of an inch. With this arrangement, the material from the inner hopper feeds first through opening 37 without admixing with the material in the outer hopper. It is to be noted that the first material falls downwardly for a short distance in neck 36 before coming to opening 37 where admixing could occur. The finely-divided material in the outer hopper does not feed, it is believed, because of the size of the particles, the inclination of wall 19, the restricted annular outlet 37 and the vertical downward flow of the first material from neck 3-6 past outlet 37 for the second material. Even during the final feeding of the first material substantially no admixing occurs.

When charging the hoppers with finely-divided calcium carbide and a mixture of magnesium particles and calcium carbide particles for desulfurizing and nodulizing molten cast iron, the gas supply to the nozzle and hoppers is shut off and the hoppers are at atmospheric pressure. Next the cover 23 is removed and plug 39 is inserted in the opening in top wall 38. The calcium-carbide-magnesium mixture charged into outer annular hopper 13 through a funnel and then the plug 39 is removed. Next the desulfurizing agent is charged into the inner circular hopper. Thereafter, the plug is replaced and cover 23 is secured gas-tightly and the apparatus is positioned above a ladle of molten cast iron which is to be treated.

To commence the injection, the gas supply valves 43. 46 are opened and valve 46 is regulated so that the gas flow through the injection tube will overcome the hydrostatic head of molten iron and the injection tube is submerged. Next shutoff valve 55 is opened whereby an unobstructed passage therethrough is provided and the treating agent in the inner hopper 31 flows past opening 37 through the o ifice opening 65, admixes with the car- 'er gas from nozzre i 9, and is discharged from the end of the injection tube into the molten cast iron. After the inner hopper is emptied without mixing, the outer hopper immediately discharges its agent through opening 37. As above-mentioned, it is to be noted that immediate successive feeding without admixing and without moving parts is achieved. The size of the orifice hole 67 in combination with the setting of the needle valve 46 regulates the rate at which the treating agent is fed. For an orifice hole of a given size. the Feed can be adjusted over a considerable range by means of the needle valve 46. The gas under pressure in the hoppers, of course, prevents any vacuum from being established and assists in delivering the treating agents.

After the agents have been introduced into the molten cast iron, the injection tube with gas still flowing therethrough is removed by lifting up the apparatus. Then the gas flow can be terminated and the hoppers recharged, as described, for treating another ladle.

It is to be understood that the instant apparatus is useful for introducing other finely-divided agents into other liquids and that the successive feed arrangement can be used with other means for providing a carrier gas.

A complete explanation of why there is no mixing during the feeding of the treating agent from the inner hopper is not known as above suggested. Obviously however, such factors as the angle of repose of the particles on the inclined wall of the outer annular hopper, the size of the annular opening, and particle size are interdependent.

The principal advantages of the present invention result from the facts that an immediate succession of feeding of two agents results and that no moving parts need be manipulated or entail wear and repair or replacement. Furthermore the concentric hopper arrangement is easy to fabricate.

It is of course apparent that various changes can be made in the disclosed apparatus without departing from the invention as defined by the following claims. For example, three or more concentric hoppers can be arranged and have the above-described features including the structure at the annular outlet so that immediate successive non-mixing feeding of three or more materials result.

We claim:

1. A pneumatic powder feeder for successively feeding quantities of finely-divided materials comprising a pressurized outer hopper having a conical lower section which terminates in an outlet, a pressurized inner vessel having a terminal peripheral edge which forms a circular opening positioned within said hopper, the entire portion of said peripheral edge being spaced about A" from the annular portion of said conical section directly opposite said edge whereby a port having a substantially uniform annular cross section is formed, said peripheral edge and said outlet being free of any moving parts whereby material can move from said inner vessel past said port without mixing and then material in said outer hopper can move immediately thereafter through said port.

2. A pneumatic powder feeder for successively feeding quantities of finely-divided materials comprising a pressurized outer hopper having a conical lower section which terminates in a circular opening, a pressurized inner vessel having a short depending circular neck with an inside diameter slightly larger than the inside diameter of said opening, said inner vessel being positioned within said outer hopper so that the entire terminal peripheral edge of said neck is spaced about /s from the annular portion of said conical section directly opposite said edge, said neck and said circular opening being free of any moving parts, and means connected to said circular opening for admixing a carrier gas with material passing through said opening and for conveying said gas and material to a place of use.

3. A pneumatic batch feeder for the injection of treating materials beneath the surface of molten iron comprising a pressurized outer hopper for one treating agent having a cylindrical upper wall and a conical lower wall terminating in a small circular port, a pressurized inner vessel for another treating agent having a cylindrical upper wall and a conical lower wall, said conical wall of said inner vessel being spaced from said conical wall of said outer hopper, said conical wall of said inner vessel having a cylindrical extension depending therefrom, the entire terminal peripheral edge of said extension being spaced about /s" from the annular portion of the conical wall of said hopper directly opposite said edge, said cylindrical extension having an internal diameter which is slightly larger than the diameter of said circular port, means connected to the top part of said hopper for admitting gas at a predetermined pressure, and means connected to said port for receiving first said one treating agent and immediately thereafter said other agent and for admixing a carrier gas with said agents.

4. A pneumatic batch feeder for feeding successively two batches of finely-divided treating agents into molten iron, comprising, a pressurized outer hopper having an inclined bottom wall which terminates in an outlet, means connected to said outlet for moving the finely divided treating agents through a conduit, a pressurized inner vessel positioned within said outer hopper, said inner vessel having a terminal edge forming a circular opening which is slightly larger than said bottom opening, and the entire portion of said peripheral edge being spaced about from the annular portion of said outer hopper directly opposite said edge.

References Cited in the file of this patent UNITED STATES PATENTS 

